Field of the Disclosure
Embodiments generally relate to input sensing and, in particular, to driving sensor electrodes for noise measurement.
Description of the Related Art
Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location, and/or motion of one or more input objects. Input objects can be at or near the surface of the proximity sensor device (“touch sensing”) or hovering over the surface of the proximity sensor device (“proximity sensing” or “hover sensing”). Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as touchpads integrated in, or peripheral to, notebook or desktop computers). Proximity sensor devices are also often used in smaller computing systems (such as touch screens integrated in cellular phones or tablet computers).
Proximity sensor devices can measure changes in mutual capacitance (or “transcapacitance”) relating to the presence of an input object in a sensing region of the sensor device. Given an array of sensing regions, transcapacitance sensing can be used to generate a capacitive image, from which one or more input objects can be resolved at a given time. Proximity sensor devices can be deleteriously affected by noise. For example, narrow-band noise can: (1) decrease sensitivity of the sensor device, leading to missed detection of input object(s); and/or (2) cause spurious peaks in the capacitive image, leading to false detection of input object(s).